Cam removal unit

ABSTRACT

A PATTERN CAM REMOVAL DEVICE FOR A ZIGZAG SEWING MACHINE WHICH PROVIDES FOR THE ELEVATION OF A PLUNGER IN RESPONSE TO THE MANUAL DEPRESSION OF A PATTERN CAM ON A CAM SEAT AND FOR THE ELEVATION OF THE PATTERN CAM UPON MANUAL DEPRESSION OF THE PLUNGER.

United States Patent Inventor Appl. No.

Filed Patented Assignee Louis l-ueett Damon Mertlnsville, NJ. 34,036

June 28, I97 I The Singer Company New York. N.Y.

CAM REMOVAL UNIT Chi-s, 7 Drawing Figs.

US. Int. Cl.

112/ 158i! D05b 3/02 l-leldolscni "1:. 2/158 [56] References Cited UNITED STATES PATENTS 2,879,732 3/1959 Casas-Robert et al ll2/l58(R) 3,457,887 7/1969 Coulombe ll2/l58(R) Primary Examiner-Richard J. Scanlan, Jr. Attorneys-Marshall J. Breen and Chester A. Williams, Jr.

ABSTRACT: A pattern cam removal device for a zigzag sewin; machine which provides for the elevation of a plunger in response to the manual depression of a pattern cam on a cam seat and for the elevation of the pattern cam upon manual depression of the plunger.

PATENIEU Juneel n 3587.491

(NV/EN! ()R. LOUIS E Damon TORNE Y CAM REMOVAL UNIT BACKGROUND OF THE INVENTION The needle of a zigzag sewing machine jogs from side to side when engaged in stitching a pattern. This jogging may be controlled by a pattern cam housed within the sewing machine and carried upon a rotating cam shaft. To change from one stitch pattern to another stitch pattern it is necessary in one known type of sewing machine to remove one pattern cam and replace it with a different pattern cam. In order to accomplish this change, the sewing machine operator must manually reach into the sewing machine housing and take hold of the pattern cam usually by means of some sort of handle which may extend upwardly from the cam surface to facilitate the cam removal. However, this removal procedure is complicated by the lack of access space open to the fingers of the operator seeking to remove the cam. Furthermore, since these cams must rotate with the cam shaft, they are tightly fixed thereon and sometimes removal without the aid of a pry is quite difficult, and an operator can break a fingernail trying to dislodge a cam. Also, if the operator must reach into the housing of the machine, the operators fingers become soiled and this may result in the fabric work piece becoming soiled.

A storage problem arises because it is necessary to provide a handle on each pattern cam for aiding in removal. The handle is in the form of a boss and sometimes amounts to a threequarter inch projection. The packaging and storage of approximately 16 cams each with such handle could result in a package about 16 inches long whereas if these handle projections could be eliminated then a package 4 inches long could be utilized and therefore result in a space savings desirable to the consumer.

SUMMARY OF THE INVENTION In accordance with the present invention, a sewing machine having a jogging or laterally oscillatory needle controlled by a pattern cam mounted on a camshaft, is provided with a cam removal mechanism incorporated into the upper portion of the camshaft. The cam removal mechanism, mounted upon a camshaft which may have a stack of permanently mounted cams thereon, is comprised of a base flange with an axially bored central hub rising therefrom about which is mounted an exchangeable pattern cam. The mechanism includes a pair of diametrically disposed ejection levers which partially seat in a clearance groove formed in the base flange and partially extend through a cutout formed in the central hub until they contact a plunger which is slidably mounted in the axial bore of the central hub. Depression of an exchangeable pattern cam onto the central hub forces the ejection levers down to the base flange and also because of the contact of the levers with the plunger, forces the plunger upward by the action of the lever on the plunger. When the plunger is depressed the opposite action occurs in that the plungers downward force raises the ejection levers which in turn ejects the exchangeable cam off of the central hub. A spring ball mechanism releasably retains the plunger in either an elevated position or a depressed position by engaging detents formed in the sides of the plunger shaft. Circumferentially, between the ejection levers are a pair of retaining levers extending outwardly of the central hub through a pair of cutouts and disposed in such a way so as to be influenced by the plunger. These retaining levers lock an exchangeable pattern cam on the central hub until released by the action of the plunger I OBJECTS OF THE INVENTION It is an object of this invention to facilitate the exchange of pattern cams by providing a pop-up cam removal device.

It is an object of this invention to provide an improved cam removal device permitting the removal of the handling boss from a pattern cam in order to permit storage of the cams in the more limited space.

It is still another object of the present invention to allow the streamlining of pattern cams so as to provide a neat and trim article more acceptable to a consumer.-

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated in the accompanying drawing in which:

FIG. 1 is a perspective view of a sewing machine bracket arm showing needle jogging pattern control cam in operative position and having this invention applied thereto;

FIG. 2 is a top plan view of the sewing machine pattern camshaft with the cam removed and showing mechanism of this invention;

FIG. 3 is an elevational view of the camshaft and cam removal mechanism of FIG. 2 along line 3-3 of FIG. 2 to show one of the ejector bellcrank levers in position when a cam seated on the base flange;

FIG. 4 is a fragmentary view similar to that of FIG. 3 showing the position of one of the ejector bellcrank levers after a cam has been unseated by depression of the plunger;

FIG. 5 is an elevational view of the camshaft and cam removal mechanism of FIG. 2 sectioned along line 5-5 of FIG. 2, to show the position of the retaining lever when the cam is seated on the base flange;

FIG. 6 is a fragmentary view similar to that of FIG. 5 showing the position of the retaining lever after the cam has been unseated by depression of the plunger, and

FIG. 7 is a perspective view of the underside of the cam removal mechanism partly broken away to show the manner in which one of the ejector bellcrank levers and one of the locking levers is fulcrummed within the pattern cam removal device.

DETAILED DESCRIPTION OF THE INVENTION Inside the casing of a cam controlled zigzag sewing machine ofthe type described in U.S. Pat. No. 2,862,468, Dec. 2, 1958, to R. E. Johnson for Ornamental Stitch Sewing Machine," there may be a stack of pattern cams for determining the pattern of lateral jogging movements which the sewing needle will follow. At least the uppermost one of these cams is exchangeable through an access opening I! in a sewing machine casing 12, as shown in FIG. I, so that a great variety of stitch patterns are possible. The sewing machine casing has a cover I3, hinged to the rear of the machine and shown opened in FIG. 1, to permit access to the pattern cams. When the lid is closed, foreign material is kept out of the machine and the exterior design of the machine becomes aesthetically complete. The pattern cam removal device of this invention is adaptable to present existing sewing machine casing designs and will not adversely influence the exterior appearance of the sewing machine.

The pattern cam removal mechanism of this invention is shown generally at 15, affixed to the top of a stack of permanently mounted cams 17 in a recess 18 provided therein. These permanently mounted cams are in turn mounted on a driven camshaft 19. The camshaft is mounted rotatably on the axle 21. A pair of screws 23 hold the pattern cam removal mechanism to the camshaft and the stack of permanently mounted cams. An alignment boss 25 may be formed on the stack of the permanently mounted cams and projects up through a cutout 26 in the cam removal mechanism, so that an exchange cam 27 can be readily synchronized onto the cam stack.

The exchangeable pattern cam 27 is a flat disc having a central aperture 29 so that it may be mounted onto the pattern cam removal mechanism and also having an offset aperture 31 so that the cam may be placed over the alignment boss and therefore be synchronized with the cam stack.

It should be appreciated that the device as set forth in this specification is the preferred embodiment. However, it is possible that the pattern cam removal device may be used with only one exchangeable pattern cam without the accompanying cam stack. Thus, the cam stack provides the usual environment for the cam removal mechanism but not the only possible construction.

The pattern cam removal mechanism has a central hub 33 which has an axial bore 35 and also has a base flange 37. A plunger 39 is mounted within the axial bore and is slidable therein. A pattern cam ejector means, including two diametrically disposed levers 41 (one not shown), is mounted into the central hub through a pair of cutouts 43. A pattern cam retaining means, including a pair of diametrically disposed levers 45 (one not shown), is mounted into the central hub through a pair of cutouts 47.

The plunger 39, as best shown in H68. 3 and 5, is a headed shaft which is axially slidable within the bore of the central hub. The shaft has two pairs of detents 49 and 60 spaced along its length, the detents of each pair being positioned diametrically opposite each other. These detents are used in conjunc tion with a plunger retaining means which includes on each side of the central hub a ball 51, a spring 53 and a screw 55 all mounted within a horizontal bore 56. The spring forces the ball into the detents to retain the plunger in one of two preselected positions, either up or down.

On the plunger shaft beneath the detents is an upper annular flange 57 and a lower annular flange 59 having a groove 611 formed between them. These flanges and groove cooperate with the pattern cam ejector means and the pattern cam retaining means in a manner which will be later described.

The pattern cam ejector levers 41 take the form of bellcrank levers each having one leg 62 longer than the other leg 63 and being formed at the point where these legs meet with an angular bend. 64. Also, at angular bend there are tab ears 65 which are inserted into recesses 66 formed in the underside of the base flange. The levers are held in place and pivoted upon tab supports 67 integral with the plate 69 held to the underside of the base flange by means of a pair of screws 71 (one not shown). The base flange has a notch 73 formed on its upper surface to accommodate flush within its surface the longer leg of the bellcrank lever when a cam is seated on the base flange. The shorter leg of the bellcrank lever protrudes through the cutout 43 into the axial bore of the central hub and rests in the groove 61. The following action is apparent from a study of FIGS. 3 and 4. When an exchangeable cam is seated on the base flange 37 of the cam removal mechanism the longer leg of the bellcrank lies flush in the notch 73 so that the cam can rest directly on the base flange. The shorter leg rests in the groove 61 and is contacted by the lower flange of the plunger shaft. The plunger at this time is in the upward position and is securedthere by the plunger retaining means. When it is desired to remove the exchange cam the plunger is depressed and the upper annular flange of the plunger shaft contacts the short arm of the bellcrank so as to cause the long lever arm to rise from the notch in the base flange whereby the cam is caused to rise from the base flange.

The two levers 45, which comprise the pattern cam retaining means are diametrically disposed partially within the eutouts 47 in the central hub. The retaining levers 45 are substantially in the shape of an inverted L and tab cars 75 protrude at the pivot point.- These tab ears are inserted into recesses (not shown) formed in the underside of the base flange in a manner similar to that used for the ejector levers. The levers are held in place and pivoted upon tab supports 77 integral with the plate 69 held to the underside of the base flange by means of screws 71 (one not shown). The levers are partially positioned within the central hub so that when the plunger is in an up position and a cam is seated on the base flange, the levers are forece forced outwardly over the seated cam by contact with the upper annular flange 57 of the raised plunger shaft. When the cam is to be exchanged, the plunger is depressed and the annular flange 57 is shifted out of contact with the retaining lever 45 whichis then free to be urged inwardly by the rising cam because it lacks the support of the annular flan e as shown in FIG. 6.

lt Wlii e understood that various changes in the details,

material, arrangements of parts and operating conditions which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principles and scope of the invention.

lclaim:

H. in a sewing machine having an endwise reciprocatory and laterally vibratory thread carrying needle, needle vibrating mechanism including a releasably mounted pattern cam operatively connected to vibrate said needle, a camshaft for mounting said pattern cam; a pattern cam removal device mounted on said camshaft having a base flange and a central hub including a plunger axially shiftable in a bore formed lengthwise in said hub, said central hub being formed with first and second cutouts, pattern cam ejector means cooperatively associated with said plunger through said first cutouts in the central hub, and pattern cam retaining means associated with said plunger through said second cutouts in the central hub whereby when the plunger is in a depressed position the ejector means elevates a cam on the central hub and when the plunger is in an elevated position the retaining means restrains a cam on the central hub.

2. The pattern cam removal device of claim 1 wherein the ejector means comprises a pair of bellcrank levers diametrically disposed partially within the central hub, one arm of each bellcrank extending radially outwardly of the central hub selectively at an acute angle to the central hub when the plunger is depressed and at a substantially right angle to the central hub when the plunger is elevated, the other arm of each bellcrank lever extending through the cutout in the central hub into a groove formed in the plunger.

3. The pattern cam removal device as claimed in claim 2 wherein said base flange is notched to accept flush within its upper surface the radially outwardly extending bellcrank arms when they are at right angle to the camshaft.

3. The pattern cam removal device as recited in claim 1 wherein the pattern cam retaining means includes a pair of levers diametrically disposed within the central hub, part of each lever extending radially outwardly of the central hub to partially overlie the pattern cam when it is mounted on the central hub and the other part of each of the levers extending through the cutout in the central hub to abut a flange formed on the plunger.

5. The pattern cam removal device as recited in claim 1 wherein the plunger may be retained selectively in either the elevated position or the depressed position by means of a spring-loaded ball which protrudes from the inner diameter of the central hub into detents formed on the plunger.

6. The pattern cam removal device as recited in claim 1 wherein the pattern cam ejector means includes a pair of bellcrank levers diametrically opposed to one another and wherein the pattern cam retaining means includes a pair of levers each disposed diametrically opposite one another and each disposed in between a pattern cam ejector lever.

7. The pattern cam removal device as recited in claim 6 wherein the levers of both the cam ejector means and the cam retaining means have tab ears extending outwardly from their respective pivot points, and a plate is detachably mounted on the underside of the base flange, said plate having upright resilient tab supports formed thereon and the underside of the base flange having recesses formed therein for accepting the tab ears of each of the levers therein pivotally supported by and locked into the base flange by the tab supports of the plate. 

